Biodegradable microcapsules and method for their preparation

Abstract

The present invention relates to a method for preparing a microcapsule and to a method for preparing a microcapsule composition. The present invention also relates to the microcapsule and the microcapsule composition per se. The present invention also relates to uses of the microcapsules and to methods involving the microcapsule, including to prepare a formulated product. The present invention also relates to the formulated product per se.

1 . A method for the preparation of a biodegradable microcapsule, the method comprising:
 (a) forming a mixture comprising one or more plant-based protein(s) in a solvent system, wherein the solvent system comprises miscible co-solvents; wherein a first co-solvent increases solubility of the plant-based protein(s), and a second co-solvent decreases solubility of the plant-based protein(s); wherein the co-solvents are added to the mixture either in concentrated or in a diluted form; and wherein the pH of the plant-based protein mixture is at least 0.5 pH units below the isoelectric point of the plant-based protein;   (b) subjecting the plant-based protein mixture to a shear treatment to form a plant-based protein hydrogel slurry;   (c) dispersing an active ingredient(s) in said plant-based hydrogel slurry to form a composition; and   (d) drying said composition to form a microcapsule.   
     
     
         2 . The method according to  claim 1 , further comprising the step of inducing at least part of the plant-based protein in the mixture to form a plant-based protein hydrogel by one or more of cooling, addition of salt, addition of anti-solvent, solvent reduction, addition of cross-linking agent, or electrostatic cross-linking. 
     
     
         3 . The method according to  claim 2 , wherein inducing at least part of the plant-based protein in the mixture to form a plant-based protein hydrogel involves a sol-gel-transition. 
     
     
         4 . The method according to  claim 1 , wherein the mixture formed in step (a) is a slurry, a dispersion, an emulsion, or a solution. 
     
     
         5 . The method according to  claim 1 , wherein drying in step (d) is done by spray drying. 
     
     
         6 . The method according to  claim 1 , wherein drying in step (d) is done by fluid bed drying. 
     
     
         7 . The method according to  claim 1 , wherein the plant-based protein(s) is selected from pea protein, potato protein, rapeseed protein, lentil protein, chickpea protein, fava bean protein, mung bean protein, sunflower seed protein, pumpkin seed protein, flax protein, chia protein, canola protein, lupine protein, alfalfa protein, moringa protein and/or rice protein. 
     
     
         8 . The method according to  claim 1 , wherein the first co-solvent is an organic acid selected from the group consisting of acetic acid, lactic acid, formic acid, propionic acid, an α-hydroxy acid, and/or a β-hydroxy acid. 
     
     
         9 . The method according to  claim 1 , wherein the second co-solvent is selected from water, ethanol, and/or ethyl acetate. 
     
     
         10 . The method according to  claim 3 , wherein the sol-gel transition is achieved by heating the protein mixture to a first temperature above the sol-gel transition temperature of the one or more plant-based protein(s) mixture, then reducing to a second temperature below the sol-gel transition temperature of the one or more plant-based protein(s) mixture to form a hydrogel. 
     
     
         11 . A method according to  claim 1 , wherein said shear treatment comprises a single shear step that involves fragmenting the plant-based protein hydrogel into fragments wherein said fragments have a d 50  as determined by laser diffraction of 0.2 to 50 microns. 
     
     
         12 . A method according to  claim 1 , wherein said shear treatment comprises a first shear step followed by a second shear step. 
     
     
         13 . A method according to  claim 12 , wherein said first shear step involves fragmenting the plant-based protein hydrogel into fragments wherein at least 80 wt % of said fragments produced in said first shear step have a particle dimension in the range 1 mm to 100 mm as determined by optical microscopy. 
     
     
         14 . A method according to  claim 12 , wherein said second shear step involves further fragmenting the plant-based protein hydrogel wherein said fragments produced in said second shear step have a d 50  as determined by laser diffraction of 0.2 to 50 microns. 
     
     
         15 . A method according to  claim 12 , wherein step (b) further comprises subjecting the plant-based protein hydrogel slurry to a solvent reduction step between said first shear step and said second shear step. 
     
     
         16 . A method according to  claim 15 , wherein said solvent reduction step comprises the steps of:
 (i) contacting the fragments of the plant-based hydrogel slurry with a non-solubilising solvent;   (ii) separating the fragments of the plant-based hydrogel slurry from the non-solubilising solvent to give a washed plant-based protein hydrogel slurry; and   (iii) optionally repeating steps (i) and (ii).   
     
     
         17 . A method according to  claim 1 , further comprising a step of altering the pH of the plant-based protein hydrogel slurry such that it is different to the isoelectric point of the plant-based protein by more than 1 pH unit. 
     
     
         18 . A method according to  claim 17 , wherein said step of altering the pH of the plant-based protein hydrogel slurry is carried out after step (b) or sequentially with step (b). 
     
     
         19 . A method according to  claim 1 , wherein the composition formed in step (c) is a shear thinning composition. 
     
     
         20 . A method according to  claim 1 , wherein the composition formed in step (c) has a viscosity in the range 1 to 10000 cP at 20° C. and 50 s −1 . 
     
     
         21 . A method according to  claim 1 , wherein the composition formed in step (c) has a protein solids content in the range 1 wt % to 25 wt % based upon the total weight of the composition. 
     
     
         22 . A method according to  claim 1 , wherein said active ingredient(s) is selected from a vitamin, a mineral, a flavour material, a fragrance material, a pro-flavour, a pro-fragrance, a flavour enhancer, a malodour counteractant, a nutraceutical, a live organism (e.g. a probiotic), a pharmaceutical, an anti-microbial agent, an anti-viral agent, an anti-inflammatory agent, a pesticide, a herbicide, a fertiliser, a fungicide, an insecticide, an animal repellent, an anti-acne agent, a skin lightening agent, an emollient, a skin moisturizing agent, a wrinkle control agent, a fabric softener active, a surface cleaning active, a skin conditioning agent, a hair conditioning agent, a dye, a pigment, and an adhesive, or combinations thereof. 
     
     
         23 . A method according to  claim 22 , wherein said active ingredient(s) is at least one fragrance material or flavour material and wherein:
 the at least one fragrance material or flavour material has a vapour pressure greater than or equal to 0.00001 Torr at 25° C.; and/or   the at least one fragrance material or flavour material has a log P greater than or equal to 3.0.   
     
     
         24 . A method according to  claim 22 , wherein said active ingredient(s) is at least one fragrance material or flavour material which is part of a fragrance or flavour wherein the fragrance or flavour contains at least 20 wt % of fragrance material(s) or flavour material(s) with a log P greater than or equal to 3.0 based upon the total weight of the fragrance or flavour. 
     
     
         25 . A method according to  claim 22 , wherein said active ingredient(s) is a vitamin or a mineral selected from the group consisting of Vitamin A, Vitamin B1, Vitamin B2, Vitamin B3, Vitamin B5, Vitamin B6, Vitamin B7, Vitamin B9, Vitamin B12, Vitamin C, Vitamin D, Vitamin E, Vitamin K, magnesium, sodium, potassium, zinc, iron, calcium, iodine, omega 3, folic acid, thiamin, riboflavin, niacin and phosphorous, or mixtures thereof. 
     
     
         26 . A method according to  claim 1 , wherein said active ingredient(s) is part of a composition comprising the active ingredient(s) and an active carrier phase. 
     
     
         27 . A method according to  claim 26 , wherein said active carrier phase is a solvent, a fat or a wax. 
     
     
         28 . A method according to  claim 1 , wherein the composition formed in step (c) comprises droplets of said active ingredient(s) or said composition comprising the active ingredient(s) and an active carrier phase having a dso as determined by laser diffraction of 0.2 to 50 microns. 
     
     
         29 . A method according to  claim 1 , wherein plant-based protein residues formed during step (d) but not incorporated into the microcapsule are recycled in the method. 
     
     
         30 . A method according to  claim 1 , further comprising subjecting the microcapsule to a post-treatment step, wherein the post-treatment step comprises a non-covalent cross-linking step, a covalent cross-linking step or a coating formation step, wherein the coating formation step comprises:
 (i) treating the microcapsule with a metal or silicon-containing compound; and/or   (ii) subjecting the microcapsule to a complex coacervation step using a polysaccharide; and/or   (iii) treating the microcapsule with an aqueous mineral solution.   
     
     
         31 . A biodegradable microcapsule obtained by or obtainable by the method of  claim 1 . 
     
     
         32 - 52 . (canceled)